Proper use of the center finder end of my edge finder

Wes,

Your description is not clear and is almost guaranteed to draw erronious answers. Go read the instructions for use of an edge finder.

Didn't come with one or I would.

Wes S

Wes,

It may be worth your while to dig around the net for a "centering spud". Really nothing more complex than a accurate conical end on a bit of round bar that will fit in a collet on your machine. In use, you can use it to hold the part in place (gently) while it's clamped, then offset your table the requisite amount.

Do you know how to dial in the center of your RT to the center of the mill spindle, using a indicator on the spindle and sweeping around the center hole of the RT ? The spud can be used for that too, though it is not a precise method. A DRO really comes nice here too, as you can set the zeros in both x and y and use them to calculate your offsets from the center of rotation of the RT. I did a course that was three months long, fulltime. About 6 weeks of it was done using an RT on a manual mill to form cam tracks, coincident arcs and precision locating of holes by assorted coordinate drilling methods using angle and distance offsets. Most of the rest of the time was trigonometry 'till we could do it in out sleep.

We all got VERY fast at dialing in a RT.

Another iten that should find it's way into your toolbox is a wiggler set. Even the Starrett ones are affordable, but a decent useable set can be found for under $10 if you dig around.

For the truly cheap fix, some placticene or putty, gobbed onto the end of the mill cutter can be used. Place a sewing needle or pin in the putty, start it turning slowly, and tweak the pointy end so it runs true (easier to do than to explain) using a pencil or splint of wood (to keep your fingers clear of the rotating pointer) You should be able to place the point within a few thou of the intersection of the layout lines without too much effort.

The Sticky Pin method above, with the putty, is efectively the same operation you would use with the pointed pin of the wiggler set.

Hope this helps a bit.

Cheers Trevor Jones

Don't know if it's the right way, but that's how I've always done it. It's good to within a thou or so.

============= see

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That is what I've always done also. Just thought I'd ask if there were more accurate techniques for small holes when trying to get it very close to right.

Thanks,

Wes S

Excellent. I figured there was more ways than dragging my thumbnail across the parting line.

Thanks for the links. Using the micrometer in x / y should have been obvious to me but was not.

Wes S

I think so. You can pick up a 'tenth' or two with your finger - it is amazingly sensitive.

Ken.

Any why not do it as you would do it with a pin? Get the center between two points along one axis, then the center along the other axis. With math, it would just require 3 points (not worth the effort). Problem is, it depends on how well the hole was deburred. That's why pluging in a pin and centering on that is much more precise. Or using a _real_ center-finder on small holes.

Nick